Methods, systems, and products for illuminating displays

ABSTRACT

Methods, systems, and products illuminate display devices. Light in a waveguide is frustrated to illuminate an array of picture elements.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/959,905 filed Dec. 3, 2010 and since issued as U.S. Pat. No.8,690,408, and incorporated herein by reference in its entirety.

BACKGROUND

Exemplary embodiments generally relate to computer graphics processing,to visual displays, to liquid crystal elements and systems, to opticalsystems and elements, and to illumination and, more particularly, todisplay driving control circuitry, to edge-lit light guides, and toedge-lighted panels.

Electronic displays are commonly used as output devices. Flat-paneldisplays, for example, are used in computers, cell phones, andentertainment systems to display movies, pictures, and other content.Conventional electronic displays, though, are back-lit. That is,conventional electronic displays are illuminated from behind.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The features, aspects, and advantages of the exemplary embodiments arebetter understood when the following Detailed Description is read withreference to the accompanying drawings, wherein:

FIG. 1 is a simplified sectional view of an illuminated display device,according to exemplary embodiments;

FIG. 2 is a sectional view of a front-lit display device, according toexemplary embodiments;

FIG. 3 is another sectional view of an illuminated display device,according to exemplary embodiments;

FIG. 4 is a block diagram illustrating the illuminated display device,according to exemplary embodiments;

FIG. 5 is a sectional view of an illuminated display device using anopaque array of picture elements, according to exemplary embodiments;

FIG. 6 is a top view of the illuminated display device, according toexemplary embodiments;

FIGS. 7-9 are schematics illustrating magnification, according toexemplary embodiments;

FIG. 10 is an exploded view of a computing device incorporating theexemplary embodiments; and

FIG. 11 is an exploded view of an instrument cluster incorporating theexemplary embodiments.

DETAILED DESCRIPTION

The exemplary embodiments will now be described more fully hereinafterwith reference to the accompanying drawings. The exemplary embodimentsmay, however, be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein. Theseembodiments are provided so that this disclosure will be thorough andcomplete and will fully convey the exemplary embodiments to those ofordinary skill in the art. Moreover, all statements herein recitingembodiments, as well as specific examples thereof, are intended toencompass both structural and functional equivalents thereof.Additionally, it is intended that such equivalents include bothcurrently known equivalents as well as equivalents developed in thefuture (i.e., any elements developed that perform the same function,regardless of structure).

Thus, for example, it will be appreciated by those of ordinary skill inthe art that the diagrams, schematics, illustrations, and the likerepresent conceptual views or processes illustrating the exemplaryembodiments. The functions of the various elements shown in the figuresmay be provided through the use of dedicated hardware as well ashardware capable of executing associated software. Those of ordinaryskill in the art further understand that the exemplary hardware,software, processes, methods, and/or operating systems described hereinare for illustrative purposes and, thus, are not intended to be limitedto any particular named manufacturer.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless expressly stated otherwise. Itwill be further understood that the terms “includes,” “comprises,”“including,” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof. It will be understood thatwhen an element is referred to as being “connected” or “coupled” toanother element, it can be directly connected or coupled to the otherelement or intervening elements may be present. Furthermore, “connected”or “coupled” as used herein may include wirelessly connected or coupled.As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items.

It will also be understood that, although the terms first, second, etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first device could be termed asecond device, and, similarly, a second device could be termed a firstdevice without departing from the teachings of the disclosure.

FIG. 1 is a simplified sectional view of an illuminated display device20, according to exemplary embodiments. A light source 22 injects oremits light 24 into a waveguide 26. The light 24 may be injected at anangle such that total internal reflection (or “TIR”) is obtained.Because the injected light 24 is totally internally reflected within thewaveguide 26, a frustrator 28 may cause frustrated light 30 to exit abottom surface 32 of the waveguide 26. The frustrated light 30 isdirected downward and onto electronic picture elements (or “pixels”).The picture elements are commonly arranged in a two-dimensional gridforming an array 40 of picture elements, as in liquid crystal, plasma,and digital light projector (or “DLP”) displays. Because the waveguide26 is arranged above the array 40 of picture elements, the frustratedlight 30 is incident an upper surface 42, thus illuminating the array 40of picture elements from above. Reflected light 44 reflects off theupper surface 42 of the array 40 of picture elements and travels backinto the waveguide 26. The reflected light 44 propagates through thewaveguide 26 and exits an outer surface 46 of the waveguide 26. Thereflected light 44 thus presents to a viewer's eye 50 an image createdby the array 40 of picture elements. FIG. 1 thus illustrates a top-litarrangement in which the array 40 of picture elements is illuminatedfrom above.

FIG. 1 thus illustrates illumination using frustrated total internalreflection (or “FTIR”). FIG. 1, though, uses frustrated total internalreflection to illuminate the array 40 of picture elements from above.Exemplary embodiments thus position, arrange, or place the waveguide 26between the array 40 of picture elements and the viewer's eye 50. Thatis, the frustrated light 30 (that exits the waveguide 26) illuminatesthe upper surface 42 of the array 40 of picture elements. The reflectedlight 44 propagates back through the waveguide 26, exits the outersurface 46 of the waveguide 26, and travels to the viewer's eye 50. Thetotal internal reflection and the frustrated total internal reflectionare well known physical and optical phenomena to those of ordinary skillin the art. This disclosure, then, need not further explain eitherphenomena.

FIG. 2 is another sectional view of the illuminated display device 20,according to exemplary embodiments. Here, though, the terminology ischanged to illustrate a front-lit orientation. The light 24 is injectedand total internal reflection is obtained. The frustrator 28 is placedor applied to an inner (or right) surface 60 of the waveguide 26, thuscausing the frustrated light 30 to exit the inner surface 60. Thefrustrated light 30 illuminates an outward surface 62 of the array 40 ofpicture elements. Reflected light 44 reflects off the array 40 ofpicture elements and travels back into the waveguide 26. The reflectedlight 44 propagates through the waveguide 26, exits the outer surface 46of the waveguide 26, and travels to the viewer's eye 50.

FIG. 3 is another sectional view of the illuminated display device 20,according to exemplary embodiments. Here the frustrator 28 is placed orapplied to the outer surface 46 of the waveguide 26. The light 24 isinjected and total internal reflection is obtained. Because thefrustrator 28 is placed or applied to the outer surface 46 of thewaveguide 26, the frustrated light 30 also enters and propagates throughan interior region of the waveguide 26. The frustrated light 30 exitsthe bottom surface 32 of the waveguide 26 and illuminates the uppersurface 42 of the array 40 of picture elements. The reflected light 44propagates back through the waveguide 26, exits the outer surface 46 ofthe waveguide 26, and travels to the viewer's eye 50. FIG. 3 thusillustrates that the frustrator 28 may be placed on either the bottomsurface 32 or the outer surface 46 of the waveguide 26, according toexemplary embodiments.

FIGS. 1-3 thus illustrate incoming light and reflected light. Theincoming light 24 propagates through the waveguide 26. The incominglight 24 is directed from the waveguide 26 and onto the array 40 ofpicture elements. The incoming light 24 reflects from the array 40 ofpicture elements and back into the waveguide 26, thus creating thereflected light 44. The incoming light 24 may travel in a firstdirection, and the reflected light 44 may travel in a second direction.The incoming light 24 and the reflected light 44 may even travel inopposite directions, such as when the incoming light 24 is normallyincident to upper surface 42 of the array 40 of picture elements.

The light source 22 illustrated in FIGS. 1-3 may inject light of anyfrequency. The light source 22, for example, may inject visible lightinto the waveguide 26. The visible light may be of any frequency in theelectromagnetic spectrum that is perceivable by the human eye 50. Thelight source 22 may even emit or inject monochromatic light (such as redor blue light). The light source 22 may even be variable, thuspermitting a human or software program to select colors of illumination.The light source 22, however, may also inject ultraviolet, infrared, andany other frequencies in the electromagnetic spectrum. The light source22 may be light emitting diodes. The light source 22 may be a singlelight emitting diode or a bank or series of light emitting diodes. Ifcost and design permit, the light source 22 may be a string of lightemitting diodes that are arranged around at least a portion of an edgeperimeter of the array 40 of picture elements. The light source 22,however, may utilize incandescent elements.

The frustrator 28 may be of any design. The frustrator 28, for example,may be any metallic cladding applied to the inner (or right) surface 32or 60 of the waveguide 26, thus causing the frustrated light 30 tolocally exit the waveguide 26. The frustrator 28, however, may be anynon-metallic coating applied to the waveguide 26. The frustrator 28, forexample, may be any polymeric or elastomeric thin film, sheet, ormaterial that is applied or adhered to the waveguide 26. The frustrator28, in other words, may be any transparent or semi-transparent materialthat extracts the frustrated light 30 from the waveguide 26.

The waveguide 26 may also be of any shape and design. The waveguide 26generally has a planar cross-section, although opposite surfaces and/orsides need not be parallel. The bottom surface 32 of the waveguide 26and the outer surface 46 of the waveguide 26, for example, may beparallel. The bottom surface 32 and the outer surface 46, however, maynot be parallel, thus having a wedge-shaped cross-section. Moreover, thewaveguide 26 may have any number of edges or sides. The waveguide 26,for example, may have a rectangular top or plan view, thus having four(4) edges or sides. The waveguide 26, however, may have a triangularshape (e.g., three sides or edges) when viewed from above (plan view).The waveguide 26, however, may have more than four edges, such as apentagonal or hexagonal shape when viewed from above. The waveguide 26may also be constructed or formed of any material, such as glass,polymer, and/or acrylic. The waveguide 26 may also be transparent oreven semi-transparent that transmits the reflected light 44.

FIG. 4 is a block diagram illustrating the illuminated display device20, according to exemplary embodiments. Here the display device 20 mayinclude a driver electronics circuit 70. Each picture element (or“pixel”) in the array 40 of picture elements may be individuallyswitched on and off by the driver electronics circuit 70. A processor 72(e.g., “μP”), application specific integrated circuit (ASIC), or othercomponent may execute a display algorithm 74 stored in a memory 76. Thedisplay algorithm 74 includes code or instructions may cause theprocessor 72 to control the driver electronics circuit 70, the array 40of picture elements, and/or the light source 20. The driver electronicscircuit 70 may apply a voltage to electrically activate any pictureelement in the array 40 of picture elements to produce any image. Thedriver electronics circuit 70, the processor 72, and the displayalgorithm 74 may cooperate to control the array 40 of picture elementsand/or to create an image by the array 40 of picture elements. Thedisplay algorithm 74 may even cause the processor 72 to produce soundsand other audible features.

FIG. 5 is another sectional view of the illuminated display device 20,according to exemplary embodiments. Here the array 40 of pictureelements may be opaque 80, thus mostly or substantially preventing lightfrom passing or propagating through the array 40 of picture elements.Conventional displays utilize transparent picture elements, thusallowing the picture elements to be illuminated from behind or below.When the picture elements are opaque, as in electronic ink devices,light cannot propagate through opaque picture elements. Becauseexemplary embodiments arrange the array 40 of picture elements below orbehind the waveguide 26, exemplary embodiments may illuminate opaquepicture elements.

As FIG. 5 illustrates, the light source 22 injects the light 24 into thewaveguide 26. The frustrator 28 causes the frustrated light 30 to exitthe inner surface 32 of the waveguide 26. The frustrated light 30illuminates the outward surface 42 of the array 40 of picture elements.Even if the individual picture elements (in the array 40 of pictureelements) are opaque, the reflected light 44 still reflects back intothe waveguide 26. The reflected light 44 propagates through thewaveguide 26, exits the outer surface 46 of the waveguide 26, andtravels to the viewer's eye 50. FIG. 5 thus illustrates that exemplaryembodiments may be used with both transparent and/or opaque pictureelements. Exemplary embodiments, in other words, may illuminate any typeof picture element, whether transparent or opaque.

FIG. 6 is a top view of the illuminated display device 20, according toexemplary embodiments. Here the illuminated display device 20 may useone or more reflectors 90 to reflect the light 24 that escapes fromedges 92 of the waveguide 26. As FIG. 6 illustrates, when the light 24is injected into an injection edge 94 of the waveguide 26, some escapinglight 24 may escape from normal and/or opposite edges 92 of thewaveguide 26. The reflectors 90 may be oriented or arranged to reflectthe escaping light 24 back into the waveguide 26.

FIGS. 7-9 are schematics illustrating magnification, according toexemplary embodiments. FIGS. 7-8 are top views of the illuminateddisplay device 20, while FIG. 9 is another sectional view. FIG. 7illustrates an image or output 100 produced by the array 40 of pictureelements, while FIG. 8 illustrates a magnified view 102 of that sameimage or output. Because exemplary embodiments place the waveguide 26between the array 40 of picture elements and the viewer's eye (asillustrated in FIGS. 1, 2 and 5), exemplary embodiments may also magnifyan output produced by the array 40 of picture elements. As FIG. 9illustrates, the waveguide 26 may optically magnify the image or outputproduced by the array 40 of picture elements. The top, outer surface 46of the waveguide 26, for example, may have a convex cross-sectionalcontour 104, thus acting as a magnifying lens to enlarge an appearanceof the image or output produced by the array 40 of picture elements.Magnification may be especially useful for cell phones, e-readers, andother devices with small displays. Exemplary embodiments, however, mayalso de-magnify (such as when the outer surface 46 of the waveguide 26has a concave cross-sectional contour).

FIG. 10 is an exploded view of a computing device 110 incorporating theexemplary embodiments. The computing device 110 may be any laptopcomputer, tablet computer, or other processor controlled device. FIG.10, though, illustrates the waveguide 26 having a snap-on configurationfor mating to the computing device 110. The waveguide 26 is constructedto include an outer frame 112. The outer frame 112 may have a resilient,peripheral lip 114 that is sized to slip-on or snap over the computingdevice 110. The outer frame 112, for example, may be designed and sizedto mate with an outer casing of any laptop computer, electronic reader(or “e-reader”), or tablet (such as the IPAD® from APPLE®, Inc.). Theouter frame 112 may thus snap onto or over the computing device 110,thus arranging the waveguide 26 above the array 40 of picture elementsof the computing device 110.

Frustration may thus be achieved. As many computing devices 110 includea thin-film screen protector 120, the screen protector 120 may double asthe frustrator 28. That is, when the outer frame 112 is snapped ontoand/or over the computing device 110, the waveguide 26 is oriented nearto or against the thin-film screen protector 120. The light source 22within the outer frame 112 injects the light into the waveguide 26, andthe thin-film screen protector 120 causes the frustrated light(illustrated as reference numeral 30 in FIGS. 1-4) to exit the waveguide26 and to shine down onto the array 40 of picture elements of thecomputing device 110. The frustrated light 30 illuminates the array 40of picture elements and reflects back through the waveguide 26 towardthe viewer's eye 50.

FIG. 10 thus illustrates a clever snap-on device that illuminates thecomputing device 110. The outer frame 112 may be snapped on or overlaidonto the computing device 110 to illuminate the array 40 of pictureelements. Exemplary embodiments may thus provide illumination ofinexpensive electronic readers (such as the AMAZON® KINDLE®) thatutilize electronic ink technology. The outer frame 112 may be sized tosnuggly fit or snap over any computing device 110 to provideillumination.

FIG. 11 is an exploded view of an instrument cluster 130 incorporatingthe exemplary embodiments. Most cars, trucks, and other vehicle have aninstrument cluster providing speed, fuel level, and other driverinformation. Exemplary embodiments may be used to illuminate theinstrument cluster 130 again using frustrated total internal reflection.The waveguide 26 is placed or arranged above the instrument cluster 130.The frustrator 28 is added or applied between the instrument cluster 130and the waveguide 26. The light source 22 injects the light 24 into thewaveguide 26, and the frustrator 28 causes the frustrated light 30 toilluminate a surface of the instrument cluster 130. The reflected light44 propagates back through the waveguide 26 and travels to the driver'seye. Exemplary embodiments thus allow the instrument cluster 130 to beinexpensively illuminated from above, instead of from behind.

While the exemplary embodiments have been described with respect tovarious features, aspects, and embodiments, those skilled and unskilledin the art will recognize the exemplary embodiments are not so limited.Other variations, modifications, and alternative embodiments may be madewithout departing from the spirit and scope of the exemplaryembodiments.

The invention claimed is:
 1. A method, comprising: injecting light intoa waveguide to create total internal reflectance; frustrating the totalinternal reflectance of the light at a surface of the waveguide;withdrawing frustrated light from the surface of the waveguide onto anarray of color controllable picture elements; and reflecting thefrustrated light from the array of color controllable picture elements;wherein the frustrated light illuminates an image created by the arrayof color controllable picture elements.
 2. The method of claim 1,further comprising reflecting the frustrated light from the array ofcolor controllable picture elements during frustration.
 3. The method ofclaim 1, further comprising applying a voltage to the array of colorcontrollable picture elements.
 4. The method of claim 1, whereininjecting the light comprises injecting visible light.
 5. The method ofclaim 1, further comprising arranging the array of color controllablepicture elements below the waveguide.
 6. The method of claim 1, furthercomprising arranging the array of color controllable picture elementsabove the waveguide.
 7. The method of claim 1, further comprisingreflecting the frustrated light from the array of color controllablepicture elements during frustration.
 8. The method of claim 1, furthercomprising applying a metallic cladding to the surface of the waveguidethat frustrates the total internal reflectance of the light.
 9. Themethod of claim 1, further comprising applying a polymeric film to thesurface of the waveguide that frustrates the total internal reflectanceof the light.
 10. The method of claim 1, further comprising applying anelastomeric film to the surface of the waveguide that frustrates thetotal internal reflectance of the light.
 11. The method of claim 1,further comprising applying a screen protector to the surface of thewaveguide that frustrates the total internal reflectance of the light.12. The method of claim 1, further comprising reflecting the light thatescapes from an edge of the waveguide back into the waveguide.
 13. Themethod of claim 1, further comprising magnifying the image created bythe array of color controllable picture elements.
 14. The method ofclaim 1, further comprising snapping the waveguide onto an outer casingcontaining the array of color controllable picture elements.
 15. Themethod of claim 14, further comprising applying a screen protector tothe surface of the waveguide snapped onto the outer casing, the screenprotector causing the frustrating of the total internal reflectance ofthe light at the surface of the waveguide.
 16. The method of claim 1,wherein injecting the light comprises injecting white light into thewaveguide.
 17. An apparatus, comprising: an array of color controllablepicture elements; a waveguide having total internal reflectance oflight; a frustrator for withdrawing frustrated light from the waveguideonto the array of color controllable picture elements; and a reflectorfor reflecting the frustrated light onto the array of color controllablepicture elements; wherein the frustrated light illuminates a coloredoutput produced by the array of color controllable picture elementsduring frustration.
 18. The apparatus of claim 17, further comprising asource injecting light into the waveguide.
 19. The apparatus of claim17, wherein the frustrator comprises a layer of material that frustratesthe total internal reflectance in the waveguide.
 20. The apparatus ofclaim 17, wherein the frustrator comprises a coating that frustrates thetotal internal reflectance in the waveguide.
 21. The apparatus of claim17, wherein the frustrator comprises a film that frustrates the totalinternal reflectance in the waveguide.
 22. The apparatus of claim 17,further comprising a circuit that applies a voltage to the array ofcolor controllable picture elements.
 23. The apparatus of claim 17,further comprising a processor that controls the array of colorcontrollable picture elements.
 24. The apparatus of claim 17, furthercomprising a magnifier that optically magnifies the output produced bythe array of color controllable picture elements.
 25. An apparatus,comprising: a waveguide; a source for injecting light to create totalinternal reflectance in the waveguide; an array of picture elements forproducing a controlled color output; a frustrator for withdrawingfrustrated light from the waveguide; and a reflector for reflecting thefrustrated light to illuminate the controlled color output produced bythe array of picture elements during frustration.
 26. The apparatus ofclaim 25, wherein the frustrator comprises a layer of material thatfrustrates the total internal reflectance in the waveguide.
 27. Theapparatus of claim 25, wherein the frustrator comprises a coating thatfrustrates the total internal reflectance in the waveguide.
 28. Theapparatus of claim 25, wherein the frustrator comprises a film thatfrustrates the total internal reflectance in the waveguide.
 29. Theapparatus of claim 25, further comprising a circuit that applies avoltage to the array of picture elements.